[Major ambulatory surgery: organizational models]. / La chirurgia ambulatoriale maggiore: modelli organizzativi.

In this essay, the authors provide a definition for those medical care facilities representing a consolidated alternative to traditional hospitalization. These facilities can be basically ascribed to the following patterns: day case surgery; day-hospital activity; home-care. Day case surgery is a complex and, in most cases, interdisciplinary procedure; this type of activity necessitates a pre-hospitalization period and often also a "protected discharge" or even a home-care service. Some specific criteria regarding day surgery activity have been defined as follows: the main criteria have a clinical nature, but they interact with others belonging to a social and structural-organizational order. The Royal College of Surgeons of United Kingdom has officially recognized in 1985 this medical care typology as one of the constituents of surgical care, and has evaluated that at least 1/3 of the overall operations could be carried out as day care surgery. In the United States, besides hospital and ambulatory surgery activity, a new pattern known as "free-standing center" has been promoted; in 1993, 35% of the operations is expected to be carried out in day case surgery centers. As far as Italy is concerned, in 1988 only day-hospital practice has been adequately recognized as an alternative medical care facility to traditional hospitalization. The Emilia Romagna region, in order to increase day case surgery activity, has issued in 1991 a list of 53 DRGs, in which day bed units treatment was possible. Up to now, however, only a small part of these diseases is treated on a day case surgery basis.

Proliferation of IL-2 activated lymphocytes preferably occurs in aggregates by cells expressing the CD57 antigen.

Aggregates of lymphocytes were investigated in long-term cultures of IL-2 stimulated peripheral blood mononuclear cells. Cells in clusters formed broad contact areas where coated pits and vesicles were often detectable. Proliferating cells were preferably found in aggregates indicating that the cell clusters represent proliferation centres in which cell division may be promoted by accessory signal transduction mediated by the close cell-to-cell contact. In bulk cultures CD57+ cells yielded increased proliferation capacity compared to CD57- cells. In addition, CD57+ cells were preferably localized in aggregates where they occupied the same position at the periphery of the clusters than the proliferating cells, suggesting that both cell types may be identical. It is discussed that the CD57 antigen represents a differentiation marker which is upregulated when CD57- cells start to proliferate assisted in cell aggregates.